The Impact Of Effects On Recorded Drums

By Jim Aikin

January 04, 2013 2:57 pm

Reverb

The purpose of reverb (reverberation) is to make
studio recordings sound as if they were done in live acoustic spaces,
such as a recital hall, gymnasium, or tiled bathroom. In the glory days
of analog recording, the “reverb” was often a cement-lined
room in the basement of the recording studio, with a speaker at one end
to fill the room with sound and a microphone at the other end to pick up
the echoes. Today’s digital reverbs are quite a bit more
convenient, and when adjusted carefully they can sound very good
indeed.

Digital reverbs come in two basic flavors: standard and
convolution. Convolution reverbs (Fig. 4) are typically more expensive
and put more demands on your computer’s CPU because more
mathematical computation is required. For many musical purposes, a
standard reverb will work just as well.

When a sound is played in
an actual room, it bounces off of the walls and other nearby surfaces.
The first few bounces can sometimes be heard as separate echoes,
especially if the room is large and the walls are concrete. These
separate echoes are created in a digital reverb as “early
reflections.” You’ll probably be able to control the level
of the early reflections as a group. The later reflections blend
together in a continuous wash of sound, which is called the decay or the
tail.

Most digital reverbs let you set the decay time, which is
the amount of time it takes the tail to die out. You may also be able to
control the density or diffusion of the tail. A low density or diffusion
setting will cause the reverb to sound rather artificial and metallic,
which may be exactly what you want. Higher density and diffusion
settings sound more natural. You may also find a “room size”
parameter that’s separate from the diffusion (Fig. 5).

Sound travels at roughly one foot per millisecond. In an acoustic
space, if your drums are 50 feet from the nearest wall, you won’t
hear any reverb at all for 100 milliseconds (1/10 second). To simulate
larger spaces, reverbs have a parameter called “predelay.”
Increasing the predelay gives a more cavernous effect, and reducing it
makes the simulated room seem smaller.

Fig. 5 The reverb included with Ableton Live 6 has some basic controls
(Predelay, Size, Decay Time, Density, Diffusion, and Dry/Wet balance)
and also a few that are less common. The Spin section adds animation to
the early reflections, while the Chorus warms up the sound.

Export Final Mix

This has been a short-and-sweet overview of
effects for recording novices. Keep an eye on future installments of
Plugged In. I’ll be covering a few other types of effects in
shorter articles.

Frequency Range

Frequency is measured in Hertz (Hz). The range of human hearing is
generally capable of anything from 20Hz to 20,000Hz. Large Hertz values
are usually stated in kiloHertz (KHz). One Hertz equals one cycle per
second. All sounds in nature contain partials (overtones) at various
frequencies. If a sound has partials at a given frequency, an equalizer
can cut or boost them without affecting the rest of the signal. But if
the sound has no partials in a certain frequency range, adjusting that
range with the equalizer will do nothing. The amount of boost or cut is
defined in decibels (dB). Decibels are usually referenced to a 0dB
level; 0dB means “no change,” not “no sound.” If
we cut a certain frequency range by 6dB, we say that it’s set to
-6dB. As a rule of thumb, 1dB is about the smallest amount of change
that an average listener can perceive. When talking about EQ, producers
and engineers often use somewhat vague terms rather than referring to
frequency ranges by the numbers. The highs in a track are generally the
frequencies above 8kHz — except that, if it’s a bass track,
the “highs” might be as low as 2kHz. These terms are
relative. The high mids (high midrange frequencies) are in the
2kHz—6kHz range, the low mids in the 800Hz—2kHz range, and
the lows are whatever is going on at the bottom. Terms such as
“nasal,” “boomy,” and “hollow” are
often used to describe EQ contours. Their meanings are fairly obvious.
As you spend time listening to tracks that have been EQ’ed, or
need to be, you’ll become more sensitive to what various frequency
ranges sound like.